fix #8862: cannot watch unicode properties like 'a.中文'

src/core/observer/watcher.js

@@ -78,15 +78,28 @@ export default class Watcher {
     if (typeof expOrFn === 'function') {
       this.getter = expOrFn
     } else {
-      this.getter = parsePath(expOrFn)
-      if (!this.getter) {
+      const bailRE = /[^\w.$]/
+      const delimiterRE = /[ ,/\\]/
+      if (bailRE.test(expOrFn)) {
+        if (process.env.NODE_ENV !== 'production') {
+          if (delimiterRE.test(expOrFn)) {
+            warn(
+              `Failed watching path: "${expOrFn}" ` +
+              'Watcher only accepts simple dot-delimited paths. ' +
+              'For full control, use a function instead.',
+              vm
+            )
+          } else {
+            warn(
+              `Failed watching path: "${expOrFn}" ` +
+              'Vue watchers only accept alphanumeric, $, or underscore naming of properties.',
+              vm
+            )
+          }
+        }
         this.getter = function () {}
-        process.env.NODE_ENV !== 'production' && warn(
-          `Failed watching path: "${expOrFn}" ` +
-          'Watcher only accepts simple dot-delimited paths. ' +
-          'For full control, use a function instead.',
-          vm
-        )
+      } else {
+        this.getter = parsePath(expOrFn)
       }
     }
     this.value = this.lazy

src/core/util/lang.js

@@ -23,11 +23,7 @@ export function def (obj: Object, key: string, val: any, enumerable?: boolean) {
 /**
  * Parse simple path.
  */
-const bailRE = /[^\w.$]/
 export function parsePath (path: string): any {
-  if (bailRE.test(path)) {
-    return
-  }
   const segments = path.split('.')
   return function (obj) {
     for (let i = 0; i < segments.length; i++) {

test/unit/modules/observer/watcher.spec.js

@@ -178,4 +178,9 @@ describe('Watcher', () => {
     new Watcher(vm, 'd.e + c', spy)
     expect('Failed watching path:').toHaveBeenWarned()
   })
+
+  it('does not support non-alphanumeric paths and throws a warning', () => {
+    new Watcher(vm, '中文', spy)
+    expect('Failed watching path:').toHaveBeenWarned()
+  })
 })